Process for forming a thermoplastic product

ABSTRACT

AN INTERGRAL THERMOPLASTIC PRODUCT IS PROVIDED FROM A PREARRANGED ARRAY OF STRAIGHT, THERMOPLASTIC FILAMENTS. THE FILAMENTS ARRANGED IN THE SAME PLANE, ARE CONVEYED TO A COMPRESSING ZONE FROM TWO OR MORE DIRECTIONS, AND CONTACTED THERAT WITH A MOLTEN FILM OF THERMOPLASTIC.   THE CONTACTED FILAMENTS ARE COOLED BY QUENCHING AND AN INTERGRAL PRODUCT IS FORMED.

y 27, 1971 H. D. DAWBARN 3,595,722

PROCESS FOR FORMING A THERMOPLASTIC PRODUCT Sheets-5hcet 1 OriginalFiled April 17, 1964 F'IG.1.

HENRY DLDAWBARN INVENTOR July 27, 1971 H. D. DAWBARN 3,595,722

PROCESS FOR FQRMING A THERMOPLASTIC PRODUCT Original Filed April 17,1964 2 She0tsShcet 2 mm; I a QXMQXM{.gm

I VV VY Y Y Y; Y vv'v Y v v HENRY a DAWBARN United States Patent C3,595,722 PRQCESS FOR FORMING A THERMOPLASTIC PRODUCT Henry ll).Dawbarn, Wayneshoro, Va., assignor to Thiokol Chemical Corporation,Bristol, Pa.

Original application Apr. 17, 1964, Ser. No. 360,673, now Patent No.3,445,319. Divided and this application Apr. 2, 1969, Ser. No. 841,641

Int. Cl. 1332b /00 U.S. Cl. 156177 7 Claims ABSTRACT OF THE DISCLUSUREAn integral thermoplastic product is provided from a prearranged arrayof straight, thermoplastic filaments. The filaments, arranged in thesame plane, are conveyed to a compressing zone from two or moredirections, and contacted thereat with a molten film of thermoplastic.The contacted filaments are cooled by quenching and an integral productis formed.

This application is a division of application Ser. No. 360,673, filedApr. 17, 1964, now U.S. Pat. 3,445,319.

The present invention relates to a novel and useful product, a processfor forming the product and a method for utilizing the product. Moreparticularly, it relates to a thermoplastic fence-like or film productwhich is suitable for a multiplicity of uses.

It is known in the art that various plastic films and the like may beutilized as tarpaulins, film coverings, moisture barriers, canopies,covers for crops, and the like. However, such plastic films tear quiteeasily after the initiation of the tear. In addition, such film productsstretch quite easily and thus are not dimensionally stable. Quiteobviously, if an inexpensive product could be produced which wouldresist such tearing, it would receive widespread acceptance in the art.

It is an object of the present invention to provide a fence-like productor film which is reinforced on at least one side with filaments. Afurther object is to provide a dimensionally stable film product.Another ObJCCI is to provide a method for depositing particles from afluid stream. A still further object is to provide a thermoplasticproduct which is useable as an inexpensive snow fence or a fence toprevent beach erosion. Another object is to provide a process forinexpensively forming such a thermoplastic product. Other objects willbecome apparent as the description of the invention proceeds.

These objects are accomplished by the present invention which providesan integral unitary thermoplastic product comprising a substantiallyunoriented thermoplastic film reinforced in at least two directions withsubstantially straight, oriented, thermoplastic filaments on at leastone side of the film.

The present invention also provides a method for depositing particlesfrom a fluid stream which comprises suspending, in the path of themoving fluid, an integral unitary thermoplastic product comprising asubstantially unoriented thermoplastic film reinforced in at least twodirections with substantially straight, oriented, thermoplasticfilaments on at least one side of the film.

In addition, the present invention provides a process for forming anintegral unitary thermoplastic product which comprises prearranging aplurality of substantially straight, oriented, thermoplastic filamentsin at least two directions, extruding a molten film of a thermoplasticon one side of said filaments and thereafter quenching the moltenthermoplastic film in contact with the filaments to form the finalproduct.

In a preferred embodiment of the present invention the thermoplastic isa polyolefin and the film is reinforced 3,595,722 Patented July 27, 1971on both sides with oriented thermoplastic filaments. In a still morepreferred embodiment, the film is formed into a plurality of stripswhich are held together by the filaments. Such a product is particularlysuitable for depositing particles from a fluid stream.

The filament and film of the present invention can be of any desiredthickness. In general, however, the film will be from about 0.5 to about10 mils in thickness and the filaments will have a denier of from about50 to about 1500.

The terms integral and unitary are used to signify that thethermoplastic product is a single entity and it represents a continuousplastic phase from each group of filaments to the film. The expressionthermoplastic signifies any plastic which becomes molten upon heating.The terminology reinforced in at least two directions means that thefilaments are laid in such a manner that the filaments immediatelybecome taut if tension is applied in the two directions. For example, iflongitudinal filaments are employed on one side of the film and thesecond set of the filaments are laid to the longitudinal filaments, thefilaments become taut upon the exertion of lengthwise or widthwisetension of the film. The phrase substantially unoriented is used in theconventional sense to mean that the film has not been stretched so as toalign the molecules. The term oriented is used in the opposite sense tomean that the filament has been stretched to orient the molecules in theplastic.

Among the various plastics which may be utilized in the practice of thepresent invention are poly (alpha-olefins) such as polypropylene andpolyethylene homopolymers or copolymers; the nylons such as 6-nylon and6,6-nylon and the polyesters such as polyethylene terephthalate and manyothers all of which are well known and widely used in the art.

The phase connected together by merely signifies that the filamentsextend from one film strip to another so that the strips are intimatelyheld together. The term fluid means any liquid or gas such as air, wateror the like. The expression extruding is used in the broadest sense tomean that the molten film strips are placed in contact with one side ofthe filaments. The molten film may be extruded onto the filaments on afiat surface but is more preferably extruded into the nip of the rollerswhich feed the filaments as is hereinafter more fully set forth.

The invention is hereinafter more fully described by reference to thedrawing.

In the accompanying drawings which illustrate preferred embodiments ofthe present invention:

FIG. 1 is a pictorial representation of the apparatus used to carry outthe process and form the product of the present invention; and

FIGS. 2 through 7 are schematic representations of products formed inaccordance with the present invention.

In FIG. 1 a plurality of oriented longitudinal filaments are led over aroller 4 in parallei relationship. Oriented diagonal filaments 2, loopedabout pins 8 on a frame 3, are also led over a roller 6 where both setsof oriented filaments meet at the nip of the rolls. A plastic supplynozzle 5 extrudes a molten polymer 9 to the nip of the two rolls whereit is cooled and forms a film which is bonded to both sets of filaments.The final product 7 is withdrawn below the rolls.

In FIG. 2, the film 10 is shown bonded to the oriented longitudinalfilaments 12 and the oriented diagonal filaments 11. FIG. 3 is a backview of the product of FIG. 2 and FIG. 4 shows the intimate bonding ofboth sets of the oriented filaments to the film. In FIG. 5, the film isextruded as a plurality of film strips 10 and only one set of diagonalfilaments 11 are employed. In FIG. 6 a set of diagonal filaments 11 arebonded to each side of the film strip 10. In FIG. 7, strips of film 10and oriented diagonal filaments 11 are utilized as in FIG. but, inaddition, oriented longitudinal filaments 12 are utilized along eachstrip of film 10.

The following examples are given to illustrate the invention and are notintended to limit it in any manner. All parts are given in parts byweight unless otherwise indicated.

EXAMPLE 1 The apparatus shown pictorially in FIG. 1 is employed to forman integral unitary thermoplastic product approximately 21 inches wide.The longitudinal filaments are spaced approximately 1 inch apart. Eachfilament is 600 denier (12 mils dia.) of a commercial polyethylenecopolymer (containing about 1% butene-l) having a density of 0.950 and amelt index of 0.4 which have been oriented by drawing 8 The samefilaments are used in the diagonal diamond pattern and are spacedapproximately 1 inch apart at 60 angles to the longitudinal filament isnot bonded to the film. The product is quite a density of 0.918 and amelt index of 2.0 is extruded from the nozzle to the nip of the rolls inthe form of a thin film at a temperature of 600 F. The rolls aremaintained at a temperature of about 65 F. by circulating water.

The final product as shown in FIGS. 1 to 4 has a film about 2 mils inthickness and all fibers are intimately bonded to the film with theexception of a very small area at the intersection of the diagonalfilaments wherein one diagonal filament passes over the other and theupper filament is not bonded to the film. The product is quite strongand tears generally terminate at the first filament encountered. It isdimensionally stable in all directions and is suitable for use intarpaulin, wrapping for cotton bales and the like.

EXAMPLE 2 The procedure of Example 1 is repeated with the exception thatthe longitudinal filaments are spaced inch apart rather than 1 inchapart as in Example 1.

The final product is the same as the product of Example 1 with theexception of the closer spacing of the longitudinal filaments.

EXAMPLE 3 The apparatus ShOlWl'l pictorially in FIG. 1 is employed toform an integral unitary thermoplastic product approximately 21 incheswide. The longitudinal filaments are ribbon filaments spacedapproximately inch apart. .Each filament is 1125 denier (0.1 inch wide)of a commercial polyethylene homopolymer having a density of 0.960 and amelt index of 0.7 which have been oriented by drawing 5 The roundfilaments of Example 1 are used in the diagonal diamond pattern and arespaced approximately 1 inch apart at 60 angles to the longitudinalfilaments. Low density polyethylene homopolymer having a density of0.918 and a melt index of 2.0 is extruded from the nozzle to the nip ofthe rolls in the form of a thin film at a temperature of 600 F. Therolls are maintained at a temperature of about 65F.

The final product *has a film about 2 mils in thickness and all fibersare intimately bonded to the film with the exception of a very smallarea at the intersection of the diagonal filaments wherein one diagonalfilament passes over the other and the top filament is not bonded to thefilm.

EXAMPLE 4 The apparatus shown pictorially in FIG. 1 is employed to forman integral unitary thermoplastic product approximately 21 inches wide.The longitudinal filaments are spaced approximately 1 inch apart. Eachfilament is 565 denier (12 mils dia.) of a commercial polypropylenehomopolymer having a density of 0.90 and a melt fiow of 3.0 which havebeen oriented by drawing 7 The same filaments are used in the diagonaldiamond pattern and are spaced approximately 1 inch apart at 60 anglesto the longitudinal filaments. The same polypropylene homopolymer isextruded from the nozzle to the nip of the rolls in the form of a thinfilm at a temperature of 500 F. The rolls are maintained at atemperature of about F.

The final product has a film about 3 mils in thickness and all fibersare intimately bonded to the film with the exception of the very smallarea at the intersection of the diagonal filaments wherein one diagonalfilament passes over the other and the filament is not bonded to thefilm.

EXAMPLE 5 The apparatus shown pictorially in FIG. 1 is employed to formintegral thermoplastic product approximately 21 inches wide. To placethe diagonal filaments on both sides of the film, the apparatus of FIG.1 is modified by using a frame containing pins on both sides of theextrusion nozzle. The filaments on each side are 600 denier (12 milsdia.) of a commercial polyethylene copolymer (containing about 1%butene-l) having a density of 0.950 and a melt index of 0.4 which havebeen oriented by drawing 8 The same filaments are used in both diagonaldiamond patterns and are spaced approximately 1 inch apart at 60 angles.Low density polyethylene homopolymer having a density of 0.918 isextruded at 600 F. from the nozzle to the nip of the roll in the form of6 thin films 2 inches wide which are spaced about 1% inches from eachother. The rolls are maintained at a temperature of about 65 F. bycirculating water.

The final product as shown in FIG. 6 has a film about 2 mils inthickness and all fibers are intimately bonded to the film with theexception of a very small area at the intersection of the diagonalfilaments wherein one diagonal filament passes over the other and thefilament is not bonded to the film. The product is quite strong.

The resulting product is suspended between two fence posts in the samemanner as a snow fence and the action is very similar to that of a snowfence. The spacing between the film sections allows much of the wind topass through while causing drifting of the snow behind the fence. Tresame product is suspended partially submerged in a running stream. Itsimilarly causes deposition of sand particles from the stream withoutmaterial interference with the stream flow. The same product can be usedto prevent beach erosion.

EXAMPLE 6 The procedure of Example 5 is repeated with the exception thatonly a single set of diagonal filaments is utilized on only one side ofthe film strips. Also, the filaments are placed inch rather than 1 inchapart as in Example 5.

The final product is similar to that of Example 5 but contains filamentson only one side of the film strips. A similar type product is shown inFIG. 5.

EXAMPLE 7 The procedure of Example 5 is repeated with the exception that3 longitudinal filaments are equidistantly spaced across each of thefilm strips. The side containing the longitudinal filaments does notcontain diagonal filaments.

The final product contains diagonal filaments on one side of the filmstrips and longitudinal filaments on the other side of each strip. Thefinal product is shown in FIG. 7.

EXAMPLE 8 The procedure of Example 5 is repeated with the exception thatthe polypropylene homopolymer filaments and film of Example 5 areemployed in the process also,

an extrusion temperature of 500 F. is employed rather than 600 F.

The resulting product is substantially identical to the product ofExample and causes deposition of the product in the same manner.

While in the above examples the longitudinal and diagonal filaments areplaced on opposite sides of the film or film strips, it is obvious thatboth could be placed on the same side so as to permit bonding of thestructure to a backing material. Also, while the diagonal strips aregenerally placed at an acute angle, it is obvious that they could beplaced at 90 to the longituidinal filaments. Other materials such asdyes, pigments and the like may be introduced into the molten structurewithout substantial alteration of the final shape structure.

Many other equivalent modifications will be apparent to those skilled inthe art from a reading of the foregoing without a departure from theinventive concept.

What is claimed is:

1. A process for forming an integral thermoplastic product whichcomprises the steps of;

prearranging in an array a plurality of substantially straight, orientedthermoplastic filaments, said filaments being substantially in the sameplane and arranged therein in at least two directions; conveying saidfilament array to a compressing zone; extending a molten film of athermoplastic in said zone, said film being substantially coextensivewith said filament array; contacting said molten film with saidfilaments on at least one side thereof, and thereafter quenching saidcontacted film to form said thermoplastic product.

2. The process of claim 1 further including the additional steps ofconveying at least one additional filament array of a plurality ofsubstantially straight oriented thermoplastic filaments to saidcompressing zone and extruding said molten film between first mentionedfilament array and said additional filament array.

3. The process of claim 1 wherein the molten film is a polyolefin.

4. The process of claim 3 wherein the polyolefin is selected from thegroup consisting of polypropylene and polyethylene.

5. The process of claim 1 wherein the filaments are polyolefinicpolymers.

6. The process of claim 5 wherein the polyolefinic polymer is selectedfrom the group consisting of polypropylene and polyethylene.

7. The process of claim 1 wherein the film is extruded in the form of atleast two separated parallel strips and the filaments contact each ofsaid strips to form the integral, final product.

References Cited UNITED STATES PATENTS 3,300,366 1/1967 Krolik 156-244X3,392,076 7/1968 Van der Pals 156244 3,445,319 5/1969 Dawbarn 156-244X3,449,187 6/1969 Bobkowicz l56244X CARL D. QUARFORTH, Primary ExaminerS. I. LECHERT, JR., Assistant Examiner US. Cl. X.R.

